Trait IntoIterator

1.0.0 · Source

pub trait IntoIterator {
    type Item;
    type IntoIter: Iterator<Item = Self::Item>;

    // Required method
    fn into_iter(self) -> Self::IntoIter;
}

Expand description

Conversion into an Iterator.

By implementing IntoIterator for a type, you define how it will be converted to an iterator. This is common for types which describe a collection of some kind.

One benefit of implementing IntoIterator is that your type will work with Rust’s for loop syntax.

§Examples

Basic usage:

let v = [1, 2, 3];
let mut iter = v.into_iter();

assert_eq!(Some(1), iter.next());
assert_eq!(Some(2), iter.next());
assert_eq!(Some(3), iter.next());
assert_eq!(None, iter.next());

Implementing IntoIterator for your type:

// A sample collection, that's just a wrapper over Vec<T>
#[derive(Debug)]
struct MyCollection(Vec<i32>);

// Let's give it some methods so we can create one and add things
// to it.
impl MyCollection {
    fn new() -> MyCollection {
        MyCollection(Vec::new())
    }

    fn add(&mut self, elem: i32) {
        self.0.push(elem);
    }
}

// and we'll implement IntoIterator
impl IntoIterator for MyCollection {
    type Item = i32;
    type IntoIter = std::vec::IntoIter<Self::Item>;

    fn into_iter(self) -> Self::IntoIter {
        self.0.into_iter()
    }
}

// Now we can make a new collection...
let mut c = MyCollection::new();

// ... add some stuff to it ...
c.add(0);
c.add(1);
c.add(2);

// ... and then turn it into an Iterator:
for (i, n) in c.into_iter().enumerate() {
    assert_eq!(i as i32, n);
}

It is common to use IntoIterator as a trait bound. This allows the input collection type to change, so long as it is still an iterator. Additional bounds can be specified by restricting on Item:

fn collect_as_strings<T>(collection: T) -> Vec<String>
where
    T: IntoIterator,
    T::Item: std::fmt::Debug,
{
    collection
        .into_iter()
        .map(|item| format!("{item:?}"))
        .collect()
}

Required Associated Types§

1.0.0 · Source

type Item

The type of the elements being iterated over.

1.0.0 · Source

type IntoIter: Iterator<Item = Self::Item>

Which kind of iterator are we turning this into?

Required Methods§

1.0.0 · Source

fn into_iter(self) -> Self::IntoIter

Creates an iterator from a value.

See the module-level documentation for more.

§Examples

let v = [1, 2, 3];
let mut iter = v.into_iter();

assert_eq!(Some(1), iter.next());
assert_eq!(Some(2), iter.next());
assert_eq!(Some(3), iter.next());
assert_eq!(None, iter.next());

Trait IntoIteratorCopy item path

§Examples

Required Associated Types§

type Item

type IntoIter: Iterator<Item = Self::Item>

Required Methods§

fn into_iter(self) -> Self::IntoIter

§Examples

Implementors§

impl IntoIterator for rand::seq::index::IndexVec

type Item = usize

type IntoIter = IndexVecIntoIter

impl IntoIterator for rustmax::rand::seq::index::IndexVec

type IntoIter = IndexVecIntoIter

type Item = usize

impl IntoIterator for Fields

type Item = Field

type IntoIter = IntoIter<Field>

impl IntoIterator for FileType

type Item = FileType

type IntoIter = Iter<FileType>

impl IntoIterator for nix::fcntl::AtFlags

type Item = AtFlags

type IntoIter = Iter<AtFlags>

impl IntoIterator for nix::fcntl::FallocateFlags

type Item = FallocateFlags

type IntoIter = Iter<FallocateFlags>

impl IntoIterator for FdFlag

type Item = FdFlag

type IntoIter = Iter<FdFlag>

impl IntoIterator for OFlag

type Item = OFlag

type IntoIter = Iter<OFlag>

impl IntoIterator for nix::fcntl::RenameFlags

type Item = RenameFlags

type IntoIter = Iter<RenameFlags>

impl IntoIterator for ResolveFlag

type Item = ResolveFlag

type IntoIter = Iter<ResolveFlag>

impl IntoIterator for SealFlag

type Item = SealFlag

type IntoIter = Iter<SealFlag>

impl IntoIterator for PollFlags

type Item = PollFlags

type IntoIter = Iter<PollFlags>

impl IntoIterator for MemFdCreateFlag

type Item = MemFdCreateFlag

type IntoIter = Iter<MemFdCreateFlag>

impl IntoIterator for SaFlags

type Item = SaFlags

type IntoIter = Iter<SaFlags>

impl IntoIterator for SfdFlags

type Item = SfdFlags

type IntoIter = Iter<SfdFlags>

impl IntoIterator for nix::sys::stat::Mode

type Item = Mode

type IntoIter = Iter<Mode>

impl IntoIterator for SFlag

type Item = SFlag

type IntoIter = Iter<SFlag>

impl IntoIterator for FsFlags

type Item = FsFlags

type IntoIter = Iter<FsFlags>

impl IntoIterator for ControlFlags

type Item = ControlFlags

type IntoIter = Iter<ControlFlags>

impl IntoIterator for InputFlags

type Item = InputFlags

type IntoIter = Iter<InputFlags>

impl IntoIterator for LocalFlags

type Item = LocalFlags

type IntoIter = Iter<LocalFlags>

impl IntoIterator for OutputFlags

type Item = OutputFlags

type IntoIter = Iter<OutputFlags>

impl IntoIterator for WaitPidFlag

type Item = WaitPidFlag

type IntoIter = Iter<WaitPidFlag>

impl IntoIterator for AccessFlags

type Item = AccessFlags

Trait IntoIterator